My daily readings 09/28/2012

Overall WordPress.com is serving about 70,000 req/sec and over 15 Gbit/sec of traffic from its NGINX powered load balancers at peak, with plenty of room to grow. Hardware configuration is Dual Xeon 5620 4 core CPUs with hyper-threading, 8-12GB of RAM, running Debian Linux 6.0. As part of high availability setup WordPress.com previously used Wackamole/Spread but has recently started to migrate to Keepalived. Even distribution of inbound requests across NGINX-based web acceleration and load balancing layer is based on DNS round-robin mechanism.